I just bought a Logitech MX510 (not MX500) optical mouse, and it doesn't work on both of my OS X machines (10.3, 10.2). I've tried using it with and without the drivers. The cursor moves, but none of the buttons work. Once I put in another USB mouse, I can use that mouse's buttons, so I doubt it's my computer's problem. I even tried my MX510 on a PC with Windows XP, and it worked without the drivers. What do you guys think I should do? Just return it and get a MX500?